Previous small studies have found low bone density among postmenopausal breast cancer survivors and accelerated bone loss after chemotherapy for breast cancer suggesting an increased risk for fractures among breast cancer survivors, according to background information in the article. Previous studies on the risk of fractures have been inconsistent.
Zhao Chen, Ph.D., M.P.H., of the University of Arizona, Tucson, and colleagues, using data from the Women's Health Initiative (WHI) Observational Study (WHI-OS), compared the occurrence of bone fractures over the course of 5.1 years in 5,298 women who reported a history of breast cancer with a reference group of 80,848 women who had no cancer history. Women reported annually in questionnaires on fractures that had been diagnosed by a physician; the fractures were categorized into four groups: hip; forearm/wrist; clinical vertebral (spine or back); and other clinical fractures.
"Using the age distribution of the entire WHI-OS cohort, we computed age-standardized fracture rates per 10,000 person-years [number of persons times number of years of observation] for breast cancer survivors and the reference group," the authors write. "Except for the hip fracture rate, fracture rates were higher in the breast cancer survivors than in the reference group. Overall, breast cancer survivors may sustain 68.6 excess fractures per 10,000 person-years compared with other women in the same age group."
The increased risk for total fractures among breast cancer survivors persisted even after adjustment for other risk factors, including fracture history lifestyle, medication use and the use of hormonal replacement therapy, the researchers found. Other factors, including age, ethnicity and depression, were associated with increased risk of fractures among breast cancer survivors. "An increased risk for total fractures was observed in all ages of breast cancer survivors in this study regardless of the time of the breast cancer diagnosis," the researchers state.
"In summary, we found increased fracture risks among breast cancer survivors," the authors conclude. "If our study results are confirmed by others, the excess number of fractures may be as high as 13,000 per year for the two million postmenopausal breast cancer survivors in the United States. Clearly, more research is needed to understand the fracture risk in this special population and to develop strategies to reduce the number of fractures among breast cancer survivors."
(Arch Intern Med. 2005; 165:552-558. Available post-embargo at www.archinternmed.com.)
Editor's Note: Co-author Margery Gass, M.D., has performed clinical research with Wyeth, Lilly, Pfizer and Proctor and Gamble. This study was supported by The National Institutes of Health contracts for Women's Health Initiative Clinical Centers and Clinical Coordinating Center. Dr. Zhao Chen was supported by an award from the National Institute of Arthritis, Musculoskeletal, and Skin Diseases, Bethesda, Md.
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